Characteristics of hydrogen-assisted catalytic ignition of n-butane/air mixtures

External heating and hydrogen-assisted catalytic ignition characteristics of n-butane (n-C4H10) were studied experimentally in a Pt-coated monolith catalytic reactor. Special attention was paid to the chemical effect of hydrogen on hydrogen-assisted ignition. A comparison of the ignition temperature for these two ignition methods shows hydrogen can lower ignition temperature. Furthermore, the ignition experiment at low hydrogen mole fraction (1.5%) shows that hydrogen has a positive chemical effect on hydrogen-assisted ignition. At constant n-butane/air flow and within certain limits of hydrogen mole fraction of mixtures, the ignition temperature changes little, whereas the time required for ignition and the cumulative amount of hydrogen decrease substantially. Consequently, high hydrogen mole fraction is favorable to hydrogen-assisted ignition. Two startup methods and thermal insulation are discussed. The co-feed method (n-butane/air/hydrogen mixtures are fed into reactor) and thermal insulation were found to be beneficial to hydrogen-assisted ignition.

► Three different catalytic ignition methods of n-butane.
► Chemical effect of hydrogen on hydrogen-assisted catalytic ignition of n-butane.
► The ignition temperature changes little in a range of hydrogen mole fraction.
► Large hydrogen mole fraction and co-feed mode are more suitable for ignition.
► Heat insulation is beneficial to hydrogen-assisted catalytic ignition.